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* [Bug tree-optimization/109638] New: unsigned > 1 ? 0 : n is not optimized to n == 1 @ 2023-04-26 21:00 pinskia at gcc dot gnu.org 2023-04-26 21:03 ` [Bug tree-optimization/109638] " pinskia at gcc dot gnu.org ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-04-26 21:00 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109638 Bug ID: 109638 Summary: unsigned > 1 ? 0 : n is not optimized to n == 1 Product: gcc Version: 13.0 Status: UNCONFIRMED Keywords: missed-optimization Severity: enhancement Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: pinskia at gcc dot gnu.org Target Milestone: --- Take: ``` unsigned test_cst (unsigned n) { if (n > 1) n = 0; return n; } unsigned test_cst1 (unsigned n) { return (n == 1); } ``` For gimple at least the second one is smaller. I suspect for x86 the second version is also faster because it uses sete rather than cmov. But these 2 functions should produce the same code. I found this on accident while looking at gcc.dg/tree-ssa/builtin-snprintf-2.c testcase. This can only be done for 1 too. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/109638] unsigned > 1 ? 0 : n is not optimized to n == 1 2023-04-26 21:00 [Bug tree-optimization/109638] New: unsigned > 1 ? 0 : n is not optimized to n == 1 pinskia at gcc dot gnu.org @ 2023-04-26 21:03 ` pinskia at gcc dot gnu.org 2023-04-27 6:42 ` rguenth at gcc dot gnu.org 2023-09-05 4:25 ` pinskia at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-04-26 21:03 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109638 --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- This should do it, I think: (simplify (cond (lt @1 integer_onep@2) integer_zerop @1) (if (TYPE_UNSIGNED (type)) (convert (eq @1 @2)))) ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/109638] unsigned > 1 ? 0 : n is not optimized to n == 1 2023-04-26 21:00 [Bug tree-optimization/109638] New: unsigned > 1 ? 0 : n is not optimized to n == 1 pinskia at gcc dot gnu.org 2023-04-26 21:03 ` [Bug tree-optimization/109638] " pinskia at gcc dot gnu.org @ 2023-04-27 6:42 ` rguenth at gcc dot gnu.org 2023-09-05 4:25 ` pinskia at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: rguenth at gcc dot gnu.org @ 2023-04-27 6:42 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109638 --- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- Hmm, but more generally if (n != x) n = 0; return n != 0; could be handled as well. Or if (n != x) n = 0; return n; -> return (n == x) * x; -1 might be another special case that CPUs can efficiently handle. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/109638] unsigned > 1 ? 0 : n is not optimized to n == 1 2023-04-26 21:00 [Bug tree-optimization/109638] New: unsigned > 1 ? 0 : n is not optimized to n == 1 pinskia at gcc dot gnu.org 2023-04-26 21:03 ` [Bug tree-optimization/109638] " pinskia at gcc dot gnu.org 2023-04-27 6:42 ` rguenth at gcc dot gnu.org @ 2023-09-05 4:25 ` pinskia at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-09-05 4:25 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109638 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |FIXED Target Milestone|--- |14.0 Status|UNCONFIRMED |RESOLVED --- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- This got fixed by r14-3036-gb57bd27cb68fdb . ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2023-09-05 4:25 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2023-04-26 21:00 [Bug tree-optimization/109638] New: unsigned > 1 ? 0 : n is not optimized to n == 1 pinskia at gcc dot gnu.org 2023-04-26 21:03 ` [Bug tree-optimization/109638] " pinskia at gcc dot gnu.org 2023-04-27 6:42 ` rguenth at gcc dot gnu.org 2023-09-05 4:25 ` pinskia at gcc dot gnu.org
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